U.S. District Judge Dan Polster in Cleveland ruled six weeks before the first scheduled federal trial over the epidemic, in a case brought by Cuyahoga and Summit counties in Ohio.

Polster also rejected efforts by Purdue, pharmacies such as Walgreens Boots Alliance Inc and drug distributors such as AmerisourceBergen Corp to exclude testimony from a Harvard Medical School economist who believes the two counties suffered as much as $223.4 million of damages from 2006 to 2018.

The decisions follow a series of rulings from Polster on Sept. 3 favoring the counties, including that they could pursue civil conspiracy claims against the defendants.

Purdue, which makes OxyContin, and its billionaire owners, the Sackler family, have been trying to negotiate a settlement over its responsibility for the opioid epidemic.

Addiction to the painkillers has claimed roughly 400,000 lives in the United States from 1999 to 2017, according to the U.S. Centers for Disease Control and Prevention.

Purdue is expected to seek bankruptcy protection this month absent a settlement, three people familiar with the matter said last week.

The Stamford, Connecticut-based company said on Monday that "negotiations continue" with state attorneys general and other plaintiffs, repeating its statement from a day earlier.

"While the company is prepared to defend itself vigorously in the opioid litigation, Purdue has made clear that it prefers a constructive global resolution," it said.

Paul Hanly, a lawyer for the counties, said Polster offered "numerous sound reasons" not to dismiss the litigation.

Polster oversees roughly 2,000 opioid lawsuits by various municipalities and entities, and the outcome of the scheduled Oct. 21 trial could affect those cases.

A bankruptcy filing would likely remove Purdue from that trial.

Polster said the Ohio counties offered enough evidence for jurors to conclude that Purdue intentionally misrepresented the risks of opioid use, for the purpose of increasing sales.

He also said the economist, Thomas McGuire, had offered "outside, neutral and authoritative sources" showing his methodology for estimating damages.

The drugmakers Allergan Plc, Endo International Plc and Mallinckrodt Plc have settled with the counties for a combined $39 million in cash.